1. Field of the Invention
This invention relates to a stiffener for an inflatable water recreation board, such as an inflatable “Stand Up Paddle” (“SUP”) board, especially for such a board constructed of drop-stitch material.
2. Background
Inflatable SUP boards are most often used for recreational purposes, such as paddling and catching waves in the ocean and paddling and riding rapids in rivers. Inflatable SUP boards, and inflatable water sports boards in general, are useful, because they are more easily transported than traditional, rigid boards made of fiberglass or hard plastics, insofar as an inflatable board can be deflated, rolled up, and put in a car trunk or even carried by a hiker, whereas traditional boards must be carried on a car's roof rack or schlepped under a surfer's arm or the surfer's head. This advantage has long been recognized in the art, for example in U.S. Pat. No. 2,018,548 to William T. Currey, issued in 1935, for an inflatable “Surf Board”, where one of the problems the invention was intended to solve was that the prior art boards could not “be readily collapsed to occupy small space for transportation.” Id., at col. 1, lines 22-24, and at col. 1, lines 38-40 (the invention could “be collapsed or inflated as desired, the device when collapsed occupying a relatively small space”). Another long-recognized disadvantage of traditional rigid boards is that, owing to their rigidity, they can injure the user or other nearby persons if the board hits them. See, e.g., U.S. Pat. No. 1,206,696 to Gulbrandsen, issued in 1916, for a “Surf Coaster”, at col. 1, lines 19-22. Inflatable boards, which are made of air-tight, rubbery materials, are less likely to cause injury to persons hit by them. Yet another disadvantage of rigid boards, especially when used in riding river rapids, is that they are easily damaged and dinged when they strike a rock. Inflatable boards can absorb and withstand these impacts, usually without any damage.
However, inflatable surfboards have always had a nagging defect, in that they are not rigid and, as a result, tend to bend and distort when used. This defect makes inflatable boards much less desirable, especially when they are used for riding waves or rapids. Various attempts at overcoming this problem have been proposed. For example, U.S. Pat. No. 3,657,753 to Le Blanc., Sr., issued in 1972, for a “Folding Inflatable Surfboard”, disclosed an inflatable surfboard that resisted longitudinal bowing by use of a flexible, but substantially non-elastic, convex panel placed over the top surface of the un-inflated board. Id., Abstract. When the board is inflated, the panel is held in a bowed condition, which secures the panel and prevents the board from flexing. Id.
In the years following World War II, efforts were made to develop an inflatable material with increased rigidity and from this work “drop-stitch” construction was created. See, e.g., U.S. Pat. No. 2,753,573 to Barker, issued in 1951, for an “Inflatable Mattress”, U.S., Pat. No. 4,251,573 to McCrory et al., issued in 1981, for “Inflatable Boat For High Speed Use”. This use of drop-stitch construction was adapted to inflatable rescue boards (see e.g., U.S. Pat. No. 3,775,782 to Rice et al., issued in 1973, for an “Inflatable Aquatic Rescue Board And Method Of Rescue”), and has in recent years found success in inflatable SUP boards. Yet, while drop-stitch construction substantially increases an inflatable board's rigidity when compared to earlier inflatable water craft, the problem has not been fully solved and the flexing problem persists.
What is needed is an inflatable board that overcomes the problem of flexing. More particularly, needed is an inflatable board of drop-stitch construction, which retains the advantages of being easily transported and posing less risk of injury to the user or others, yet provides increased rigidity and a resistance to bowing and flexing.